Robin Roberts Leaves 'GMA' Early -- 'Some Things Happened at Home'

Robin Roberts just announced ... she will begin her medical leave from "Good Morning America" TODAY ... one day ahead of schedule ... after "some things happened at home."

Roberts -- who was recently diagnosed with MDS -- had originally planned to stay through tomorrow before leaving the show to prepare for her bone marrow transplant.

But this morning, an emotional Roberts explained, "I had planned to let tomorrow be the last day ... and then some things happened at home and I wanna take care of that before I begin my treatment next week."

Country star Martina McBride performed a song for Robin ... and Roberts, with a smile on her face, tearfully sang along.